The present invention relates to mechanisms for transporting small amounts of material from a supply to another location a short distance away. In particular, the invention is a ladle transport adapted for conveying small discrete amounts of material, in pellets or in capsules for example, from a supply to the combustion chamber of a combustion elemental analysis instrument in which material to be analyzed is burned and the combustion products analyzed to determine the quantitative presence of a particular element, eg. carbon, hydrogen; nitrogen. For convenience and clarity of understanding, the transport system of this invention is hereinafter described with particular reference to its adaptation for use with such a combustion elemental analytical instrument, but it will be understood that it would also be useful in other contexts.
In order to provide accurate analysis with the aforesaid types of analytical instruments the test material is customarily burned in a controlled atmosphere, eg. in pure oxygen, at a particular pressure so that means is provided for purging the combustion area between successive burnings and to have the combustion area sealed for providing and preserving the controlled atmosphere in which the combustion takes place. Provision is, of course, made for opening the chamber to receive the sample material to be burned and to be able to withdraw the ash residue after each burning. It is also desirable to be able to feed successive samples of test materials from a magazine supply into the combustion chamber and to remove the ash after each burning by some sort of transport mechanism that can be sealed from the outside, but without having to purge the interior after each burning and removal of the ash from the combustion chamber.
At present, in one known type of combustion analysis instrument, material to be analyzed is loaded into a platinum capsule which is then placed in a ladle boat. The end of a transfer tube is opened and the loaded boat is inserted. The tube is closed and a purge gas is flowed through the system to eliminate contaminants entering when the tube is opened, then the loaded boat is moved through the transfer tube to the combustion chamber by a magnet moved manually along the outside of the tube. After combustion, the boat with the capsule containing ash is magnetically withdrawn from the combustion chamber and back to the end of the tube which is opened for the first capsule containing ash to be removed from the boat and replaced by a new capsule containing new sample material. Due to the foregoing manual loading and feeding and having to purge the system for each load, the procedure is cumbersome and severely limits the time required for a series of analyses. Automatic loading systems have been proposed in which some sort of mechanical transport mechanism, adapted for automated sequential operation is employed, but in previously known mechanical systems the mechanisms for carrying capsules from a magazine to the cmbustion chamber and then to a residue receiving and holding tube or cavity are rather complex and take up a disproportionate amount of space.
It, is therefore, an object of the present invention to provide a mechanical transport system for the above purpose, and in general, for transporting discrete samples from a magazine supply a short distance and then back to be deposited in residue receiving recepticle, that is compact, that is adapted to be sealed, that is mechanically simple, and that is adapted to be operated sequentially by automated controls.